This invention relates to a remote monitoring system transmitter for use in an underground utility vault and, more particularly, to a conversion kit whereby the type of transmitter can be changed without changing the existing transmitter cabling, even though the transmitter cable terminations are different.
The need for remote monitoring capability of operating conditions existing at individual transformers in an underground vault of an underground network power distribution system is well known in the art. Ideally, information such as three phase load currents on transformers, status of network protectors, oil temperatures of transformers in excess of specified limits, water levels, fuse status, and surrounding environmental concerns such as vault access, air temperatures, etc., are required so that critical decisions can be made regarding network switching, problem analysis, peak load analysis, contingency studies, etc.
For example, the Remote Monitoring System manufactured by BAE Systems is typical of the current approach to meeting these requirements. This apparatus is a power line carrier system designed specifically to use network distribution feeders as the communications medium between network distribution transformers, located in underground vaults, and the substation. The system consists of a transmitter and sensors installed at the distribution transformer to be monitored and a receiver located at the network substation. The sensors provide input data, such as transformer load currents and network protector position, to the transmitter, which periodically transmits the information, including vault identification, by power line carrier signal over the distribution feeder to the substation receiver. Coupling of the signal to the feeder is accomplished by direct connection to the low voltage side of the network distribution transformer. At the substation, the signal is magnetically detected from the feeder by means of a pick-up coil attached to the feeder cable. Direct electrical connection to the feeder is not required. The substation receiver decodes the signal information and stores the data for presentation on demand. The receiver is microprocessor controlled. In addition to cross referencing data to the actual vault identification, the receiver produces the data in numerous “by exception” formats controlled by command inputs. Network protector status and transformer loading prior to and following feeder outages, are available, thereby reducing the need for feeder patrols. Peak period transformer loading data is instantly available for the whole network simultaneously for more accurate planning than was previously possible with manual measurements, which are not concurrent. Monitoring of spot networks, local areas, and critical locations for maintenance work can be achieved remotely without the need for field crews to be on-site to check status.
Up to now, the above-described transmitter, identified as Model 2391, has been in the form of a sealed cylindrical tube, having connectors on a first end for connection to complementary terminations at a first end of an otherwise environmentally sealed cable harness. The cable harness is connected at its second end to the network distribution transformer in the vault. To protect the transmitter connectors and cable harness terminations from the environment in the vault, which may be wet, the cable harness is equipped with a boot at its first end. After the cable harness terminations are mated to the transmitter connectors, the boot is slipped over the first end of the cylindrical transmitter and environmentally sealed thereto by means of a large hose, or ribbon, clamp.
Due to technological advances and the need for additional monitoring features, the transmitter has been redesigned, and may be identified as Model 2777. With this redesign, the transmitter is no longer in the form of a cylindrical tube, but instead now has a generally rectilinear and boxlike configuration. Additionally, the connectors on the new transmitter are different from the connectors on the old transmitter. Thus, if an old transmitter is to be replaced by a new transmitter, the new transmitter cannot be connected directly to the existing cable harness. It would be desirable to be able to connect the new transmitter to the existing cable harness because this would obviate the need to change internal wiring of the associated transformer, an arduous and time consuming task.
The environment in the underground vault requires that the transmitter and its connections be environmentally sealed. Since the new transmitter design is boxlike instead of cylindrical, the old manner of sealing the transmitter/cable connections is not possible. It would therefore be desirable to be able to provide a sealed environment for the new transmitter design and the transmitter/cable connections.